更换源

没有更换源，直接用sudo apt install xxx会十分的慢，因为它是从国外的服务器中下载，所以我选择换用国内的源，体验一下飞一般的下载的快乐。

操作步骤指南博客

这是原博==

其实就是那么几步，首先

#备份源文件列表
sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup  #其实后面那个文件名称可以随便填，只是留个副本

然后打开源文件列表（我用的是vim，原博用的是别的文档操作的软件）

sudo vim /etc/apt/sources.list

在文件头部插入：

#  阿里源
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse

也可以换别的源，原博给了好多源，反正我用的是阿里源，所以这里只写阿里源。

最后刷新列表。

sudo apt-get update
sudo apt-get upgrade
sudo apt-get install build-essential

就成功了。